Loss circulation compositions (LCM) having Portland cement clinker

ABSTRACT

Portland cement clinker LCMs that include Portland cement clinker to mitigate or prevent lost circulation in a well are provided. A Portland cement clinker LCM may include Portland cement clinker, Portland cement, a carrier fluid, and an inorganic consolidation activator. Another Portland cement clinker LCM may include Portland cement clinker and a crosslinked fluid, such as a polyuronide crosslinked via calcium ions or a polysaccharide crosslinked via divinyl sulfone. Yet another Portland cement clinker LCM may include Portland cement clinker and polymer fibers or particulate glass. Methods of lost circulation control using a Portland cement clinker LCM are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.62/535,024 filed Jul. 20, 2017, and titled “LOSS CIRCULATIONCOMPOSITIONS (LCM) HAVING PORTLAND CEMENT CLINKER.” For purposes ofUnited States patent practice, this application incorporates thecontents of the Provisional Application by reference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to controlling lost circulationin a well, such as during drilling or cementing operations. Morespecifically, embodiments of the disclosure relate to lost circulationmaterials (LCMs).

Description of the Related Art

Various challenges are encountered during drilling and productionoperations of oil and gas wells. For example, fluids used in drilling,completion, or servicing of a wellbore can be lost to the subterraneanformation while circulating the fluids in the wellbore. Such lostcirculation can be encountered during any stage of operations and occurswhen fluid (such as drilling fluid) pumped into a well returns partiallyor does not return to the surface. Lost circulation may be associatedwith problems with well control, borehole instability, pipe sticking,unsuccessful production tests, inadequate zonal isolation, poorhydrocarbon production after well completion, and formation damage dueto plugging of pores and pore throats by mud particles. Lost circulationcan occur in various formations, such as naturally fractured formations,cavernous formations, and high permeability formations. The extent ofthe fluid loss and the ability to control the lost circulation with anLCM depends on the type of formation in which the lost circulationoccurs, as well as on the dimensions of the loss circulation zone. Thecosts incurred in lost circulation situations may be due to lost time,losses of drilling fluids, and losses of production.

SUMMARY

Lost circulation materials (LCMs) are used to mitigate lost circulationby blocking the path of the wellbore fluid (for ex., a drilling fluid)into the formation. The type of LCM used in a lost circulation situationdepends on the extent of lost circulation and the type of formation.Lost circulation materials may include different types, such as fibrousmaterials, flaky materials, granular materials, and so on. Existing LCMsmay perform poorly in mitigation and prevention of lost circulation incertain formations. For example, large vugular openings within the losszones of karst formations (e.g., dolomite formations) may consume allfluids and solids are pumped downhole during drilling. This includescement, large pieces of ground marble, and various lost circulationmaterials in the forms of fibers, flakes, particles, high fluid losssqueezes, and settable resins. Existing LCMs are problematic in suchformations as they do not provide a way to form a mechanically competentand pressure resistant seal, especially when the losses are severe.

Cement clinker is produced during the production of cement in a cementkiln, typically at temperatures around 1600° C. After cooling, theclinker may contain a mixture a powder, irregularly shaped chunks, andspherical balls. To produce usable cement, the cement clinker is mixedwith grinding aids and anti-flash setting agents and ground to a desiredparticle size. However, when clinker is mixed with water it does not setlike cement and common cement set accelerators are not effective inactivating clinker material and producing a cohesive set cement withcompressive strengths in the range suitable for ground cement. Acontributing factor for the clinker behavior is due to the decrease inthe reactive surface area because of the larger particle sizes, and theinability of water to reach and hydrate the all the availablecementiceous components. A portion of clinker may include relativelylarger particles that are difficult to suspend in an aqueous carrierfluid, a problem compounded by the specific gravity of cement beingabout 3.15 times higher than the specific gravity of water.

Embodiments of the disclosure include Portland cement clinker LCMs thatinclude Portland cement clinker to mitigate or prevent lost circulationin a well. Advantageously, the different particle sizes of the clinkerused in the cement clinker LCM compositions can pack together to formtightly packed plugs of relatively low permeability. Moreover, evenpartial setting of the clinker or cement used in the cement clinkercomposition can decrease the permeability of the formed plugs andincrease the strength of the plug and further improve the mitigation orprevention of loss of wellbore fluids in lost circulation zones.

In one embodiment, an LCM composition is provided that includes Portlandcement clinker, cement, a carrier fluid, and an inorganic consolidationactivator selected to consolidate the clinker in the composition to forma plug when introduced into a lost circulation zone. In someembodiments, the carrier fluid is an aqueous carrier fluid that includesat least one of diutan gum, xanthan gum, and welan gum. In someembodiments, the Portland cement clinker is ASTM International Type Icement clinker, ASTM International Type V cement clinker, API Class Acement clinker, or API Class G cement clinker. In some embodiments, thecement is API Class G cement. In some embodiments, the inorganicconsolidation activator includes a silicate salt. In some embodiments,the inorganic consolidation activator includes at least one of sodiumsilicate, calcium aluminate, calcium chloride, sodium aluminate, andpotassium silicate. In some embodiments, the inorganic consolidationactivator is an amount in the range of about 1.0 weight of the totalweight (w/w %) to about 3.0 w/w %. In some embodiments, the weight ratioof carrier fluid to clinker is 1:1. In some embodiments, the weightratio of cement clinker to cement is in the range of 60:40 to 70:30. Insome embodiments, the LCM composition includes a plurality of polymerfibers. In some embodiments, the polymer fibers include polypropylenefibers. In some embodiments, the LCM composition includes particulateglass having an aspect ratio greater than or less than 1. In someembodiments, the particulate glass includes a plurality of glass fibersor a plurality of glass flakes.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM includes Portland cement clinker,cement, a carrier fluid, and an inorganic consolidation activatorselected to consolidate the clinker in the composition to form a plugwhen introduced into a lost circulation zone. In some embodiments, thecarrier fluid is an aqueous carrier fluid that includes at least one ofdiutan gum, xanthan gum, and welan gum. In some embodiments, thePortland cement clinker is ASTM International Type I cement clinker,ASTM International Type V cement clinker, API Class A cement clinker, orAPI Class G cement clinker. In some embodiments, the cement is API ClassG cement. In some embodiments, the inorganic consolidation activatorincludes a silicate salt. In some embodiments, the inorganicconsolidation activator includes at least one of sodium silicate,calcium aluminate, calcium chloride, sodium aluminate, and potassiumsilicate. In some embodiments, the inorganic consolidation activator isan amount in the range of about 1.0 weight of the total weight (w/w %)to about 3.0 w/w %. In some embodiments, the weight ratio of carrierfluid to clinker is 1:1. In some embodiments, the weight ratio of cementclinker to cement is in the range of 60:40 to 90:10. In someembodiments, the method includes maintaining the LCM in contact with thelost circulation zone for a time period, such that the LCM forms a plug.In some embodiments, the time period is in the range of 24 hours to 76hours. In some embodiments, the lost circulation zone is located in akarst formation. In some embodiments, introducing the lost circulationmaterial (LCM) into the wellbore includes mixing the LCM with water toform a mixture and pumping the mixture into the lost circulation zone.

In another embodiment, an LCM composition is provided that includesPortland cement clinker and a polyuronide selected to crosslink in thepresence of calcium dissolved from the clinker by an aqueous fluid. Insome embodiments, the Portland cement clinker includes ASTMInternational Type I cement clinker, ASTM International Type V cementclinker, API Class A cement clinker, or API Class G cement clinker. Insome embodiments, the polyuronide includes an alginate or a pectin. Insome embodiments, the polyuronide includes apple pectin or citruspectin. In some embodiments, the polyuronide is an amount in the rangeof 0.5 weight of the total weight (w/w %) by weight of water to 3 w/w %by weight of water. In some embodiments, the cement clinker includes aplurality of particles each having a diameter greater than 1 centimeter.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM composition includes Portland cementclinker and a polyuronide selected to crosslink in the presence ofcalcium dissolved from the clinker. In some embodiments, the Portlandcement clinker includes ASTM International Type I cement clinker, ASTMInternational Type V cement clinker, API Class A cement clinker, or APIClass G cement clinker. In some embodiments, the polyuronide includes analginate or a pectin. In some embodiments, the polyuronide includesapple pectin or citrus pectin. In some embodiments, the polyuronide isan amount in the range of 0.5 weight of the total weight (w/w %) byweight of water to 3 w/w % by weight of water. In some embodiments, thecement clinker includes a plurality of particles each having a diametergreater than 1 centimeter. In some embodiments, the method includesmaintaining the LCM in contact with the lost circulation zone for a timeperiod, such that the LCM forms a plug. In some embodiments, the timeperiod is in the range of 24 hours to 76 hours. In some embodiments, thelost circulation zone is located in a karst formation. In someembodiments, introducing the lost circulation material (LCM) into thewellbore includes mixing the LCM with water having dissolved polyuronideto form a mixture and pumping the mixture into the lost circulationzone.

In another embodiment, an LCM composition is provided that includesPortland cement clinker, a biopolymer, and divinyl sulfone (DVS), thebiopolymer selected to crosslink in the presence of the DVS. In someembodiments, the Portland cement clinker includes ASTM InternationalType I cement clinker, ASTM International Type V cement clinker, APIClass A cement clinker, or API Class G cement clinker. In someembodiments, the biopolymer includes at least one of: xanthan gum,hydroxyethyl cellulose, diutan gum, welan gum and guar gum. In someembodiments, the biopolymer includes a combination of xanthan gum andguar gum. In some embodiments, the biopolymer is an amount in the rangeof 0.5 weight of the total weight (w/w %) to 0.8 w/w %. In someembodiments, the weight ratio of biopolymer to DVS is in the range of1:1 to 1:0.5. In some embodiments, the LCM composition includes sodiumhydroxide in an amount sufficient to adjust the pH of a solution of thepolysaccharide and DVS to at least 8.5. In some embodiments, the cementclinker includes a plurality of particles each having a diameter greaterthan 1 centimeter.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM composition includes Portland cementclinker, a biopolymer, and divinyl sulfone (DVS), the biopolymerselected to crosslink in the presence of the DVS. In some embodiments,the Portland cement clinker includes ASTM International Type I cementclinker, ASTM International Type V cement clinker, API Class A cementclinker, or API Class G cement clinker. In some embodiments, thebiopolymer includes at least one of: xanthan gum, hydroxyethylcellulose, diutan gum, welan gum and guar gum. In some embodiments, thebiopolymer includes a combination of xanthan gum and guar gum. In someembodiments, the biopolymer is an amount in the range of 0.5 weight ofthe total weight (w/w %) to 0.8 w/w %. In some embodiments, the weightratio of biopolymer to DVS is in the range of 1:1 to 1:0.5. In someembodiments, the LCM composition includes sodium hydroxide in an amountsufficient to adjust the pH of the LCM composition to at least 8.5. Insome embodiments, the cement clinker includes a plurality of particleseach having a diameter greater than 1 centimeter. In some embodiments,the method includes maintaining the LCM in contact with the lostcirculation zone for a time period, such that the LCM forms a plug. Insome embodiments, the time period is in the range of 24 hours to 76hours. In some embodiments, the lost circulation zone is located in akarst formation. In some embodiments, introducing the lost circulationmaterial (LCM) into the wellbore includes mixing the LCM with water toform a mixture and pumping the mixture into the lost circulation zone.

In another embodiment, an LCM composition is provided that includesPortland cement clinker, a carrier fluid, and a plurality of polymerfibers. In some embodiments, the plurality of polymer fibers includes aplurality of polypropylene fibers. In some embodiments, the plurality ofpolymer fibers each have a length in the range of 1 millimeters (mm) to6 millimeters. In some embodiments, the plurality of polymer fibersincludes a plurality of polyacrylonitrile fibers. In some embodiments,the plurality of polymer fibers is an amount in the range of 0.25 weightof the total weight (w/w %) to 1.0 w/w %. In some embodiments, thecarrier fluid includes at least one of diutan gum, xanthan gum, andwelan gum. In some embodiments, the Portland cement clinker includesASTM International Type I cement clinker, ASTM International Type Vcement clinker, API Class A cement clinker, or API Class G cementclinker. In some embodiments, the LCM composition includes cement. Insome embodiments, the cement includes API Class G cement. In someembodiments, the weight ratio of cement clinker to cement is in therange of 60:40 to 90:10.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM composition includes Portland cementclinker, a carrier fluid, and a plurality of polymer fibers. In someembodiments, the plurality of polymer fibers includes a plurality ofpolypropylene fibers. In some embodiments, the plurality of polymerfibers each have a length in the range of 1 millimeters (mm) to 6millimeters. In some embodiments, the plurality of polymer fibers is anamount in the range of 0.25 weight of the total weight (w/w %) to 1.0w/w %. In some embodiments, the carrier fluid includes at least one ofdiutan gum, xanthan gum, and welan gum. In some embodiments, thePortland cement clinker includes ASTM International Type I cementclinker, ASTM International Type V cement clinker, or API Class G cementclinker. In some embodiments, the LCM composition includes cement. Insome embodiments, the cement includes API Class G cement. In someembodiments, the weight ratio of cement clinker to cement is in therange of 60:40 to 90:10. In some embodiments, the method includesmaintaining the LCM in contact with the lost circulation zone for a timeperiod, such that the LCM forms a plug. In some embodiments, the timeperiod is in the range of 24 hours to 76 hours. In some embodiments, thelost circulation zone is located in a karst formation. In someembodiments, introducing the lost circulation material (LCM) into thewellbore includes mixing the LCM with water to form a mixture andpumping the mixture into the lost circulation zone.

In another embodiment, an LCM composition is provided that includesPortland cement clinker, a carrier fluid, and particulate glass havingan aspect ratio greater than 1 or less than 1. In some embodiments, theparticulate glass is a plurality of glass fibers each have a length inthe range of 1 millimeters (mm) to 6 millimeters. In some embodiments,the particulate glass is an amount in the range of 0.25 weight of thetotal weight (w/w %) to 2.0 w/w %. In some embodiments, the carrierfluid is an aqueous carrier fluid that includes at least one of diutangum, xanthan gum, and welan gum. In some embodiments, the Portlandcement clinker includes ASTM International Type I cement clinker, ASTMInternational Type V cement clinker, API Class A cement clinker, or APIClass G cement clinker. In some embodiments, the LCM compositionincludes cement. In some embodiments, the cement includes API Class Gcement. In some embodiments, the weight ratio of cement clinker tocement is in the range of 60:40 to 90:10.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM composition includes Portland cementclinker, a carrier fluid, and particulate glass having an aspect ratiogreater than 1 or less than 1. In some embodiments, the particulateglass each have a length in the range of 1 millimeters (mm) to 6millimeters. In some embodiments, the particulate glass is an amount inthe range of 0.25 weight of the total weight (w/w %) to 2.0 w/w %. Insome embodiments, the carrier fluid is an aqueous carrier fluid thatincludes at least one of diutan gum, xanthan gum, and welan gum. In someembodiments, the Portland cement clinker includes ASTM InternationalType I cement clinker, ASTM International Type V cement clinker, APIClass A cement clinker, or API Class G cement clinker. In someembodiments, the LCM composition includes cement. In some embodiments,the cement includes API Class G cement. In some embodiments, the weightratio of cement clinker to cement is in the range of 60:40 to 90:10. Insome embodiments, the method includes maintaining the LCM in contactwith the lost circulation zone for a time period, such that the LCMforms a plug. In some embodiments, the time period is in the range of 24hours to 76 hours. In some embodiments, the lost circulation zone islocated in a karst formation. In some embodiments, introducing the lostcirculation material (LCM) into the wellbore includes mixing the LCMwith water to form a mixture and pumping the mixture into the lostcirculation zone.

In another embodiment, an LCM composition is provided that includesPortland cement clinker and a carrier fluid. In some embodiments, thecarrier fluid is an aqueous carrier fluid that includes at least one ofdiutan gum, xanthan gum, and welan gum. In some embodiments, the carrierfluid us a drilling fluid. In some embodiments, the carrier fluid is anon-aqueous fluid. In some embodiments, the carrier fluid is an aqueousdrilling fluid. In some embodiments, the Portland cement clinkerincludes ASTM International Type I cement clinker, ASTM InternationalType V cement clinker, API Class A cement clinker, or API Class G cementclinker. In some embodiments, the weight ratio of carrier fluid toclinker is 1:1. In some embodiments, the LCM composition includes aplurality of polymer fibers. In some embodiments, the polymer fibersinclude polypropylene fibers. In some embodiments, the LCM compositionincludes particulate glass having an aspect ratio greater than or lessthan 1. In some embodiments, the particulate glass includes a pluralityof glass fibers or a plurality of glass flakes.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM includes Portland cement clinker anda carrier fluid. In some embodiments, the carrier fluid is an aqueouscarrier fluid that includes at least one of diutan gum, xanthan gum, andwelan gum. In some embodiments, the carrier fluid us a drilling fluid.In some embodiments, the carrier fluid is a non-aqueous fluid. In someembodiments, the carrier fluid is an aqueous drilling fluid. In someembodiments, the Portland cement clinker includes ASTM InternationalType I cement clinker, ASTM International Type V cement clinker, APIClass A cement clinker, or API Class G cement clinker. In someembodiments, the weight ratio of carrier fluid to clinker is 1:1. Insome embodiments, the LCM composition includes a plurality of polymerfibers. In some embodiments, the polymer fibers include polypropylenefibers. In some embodiments, the LCM composition includes particulateglass having an aspect ratio greater than or less than 1. In someembodiments, the particulate glass includes a plurality of glass fibersor a plurality of glass flakes.

In another embodiment, an LCM composition is provided that includesPortland cement clinker, cement, and a carrier fluid. In someembodiments, the carrier fluid is an aqueous carrier fluid that includesat least one of diutan gum, xanthan gum, and welan gum. In someembodiments, the Portland cement clinker includes ASTM InternationalType I cement clinker, ASTM International Type V cement clinker, APIClass A cement clinker, or API Class G cement clinker. In someembodiments, the cement is API Class G cement. In some embodiments, theweight ratio of carrier fluid to cement clinker is 1:1. In someembodiments, the weight ratio of cement clinker to cement is in therange of 60:40 to 90:10. In some embodiments, the LCM compositionincludes a plurality of polymer fibers. In some embodiments, the polymerfibers include polypropylene fibers. In some embodiments, the LCMcomposition includes particulate glass having an aspect ratio greaterthan or less than 1. In some embodiments, the particulate glass includesa plurality of glass fibers or a plurality of glass flakes.

In another embodiment, a method to control lost circulation in a lostcirculation zone in a wellbore is provided that includes introducing alost circulation material (LCM) into the wellbore such that the LCMcontacts the lost circulation zone and reduces a rate of lostcirculation into the lost circulation zone as compared to a periodbefore introducing the LCM. The LCM includes Portland cement clinker,cement, and a carrier fluid. In some embodiments, the carrier fluid isan aqueous carrier fluid that includes at least one of diutan gum,xanthan gum, and welan gum. In some embodiments, the Portland cementclinker includes ASTM International Type I cement clinker, ASTMInternational Type V cement clinker, API Class A cement clinker, or APIClass G cement clinker. In some embodiments, the cement is API Class Gcement. In some embodiments, the weight ratio of carrier fluid to cementclinker is 1:1. In some embodiments, the weight ratio of cement clinkerto cement is in the range of 60:40 to 90:10. In some embodiments, theLCM composition includes a plurality of polymer fibers. In someembodiments, the polymer fibers include polypropylene fibers. In someembodiments, the LCM composition includes particulate glass having anaspect ratio greater than or less than 1. In some embodiments, theparticulate glass includes a plurality of glass fibers or a plurality ofglass flakes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of the heat of hydration of Portland cement clinker andxanthan gum compositions with and without sodium silicate in accordancewith embodiments of the disclosure;

FIG. 2 a plot of viscosity measurements on the carrier fluid havinghydroxyethyl cellulose and divinyl sulfone (DVS) as a crosslinking fluidused in various Portland cement clinker compositions in accordance withembodiments of the disclosure;

FIG. 3 is a plot of viscosity measurements on the carrier fluid havingguar gum and xanthan gum with DVS as a crosslinking fluid used invarious Portland cement clinker compositions in accordance withembodiments of the disclosure;

FIG. 4 is a plot of the heat of hydration of Portland cement clinkercompositions having different particle sizes of ASTM Type I cementclinker in accordance with embodiments of the disclosure;

FIG. 5 is a plot of the cumulative heat of hydration of Portland cementclinker compositions having two clinker particle sizes of ASTM Type Icement clinker in accordance with embodiments of the disclosure; and

FIG. 6 is a plot of the filter cake strength (as indicated by theUltrasonic Cement Analyzer (UCA) strength) for various Portland cementclinker compositions having API Class G cement with and without fibersin accordance with embodiments of the disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with referenceto the accompanying drawings, which illustrate embodiments of thedisclosure. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

As used herein, the term “cement clinker” or “Portland cement clinker”refers to a substance distinct from cement and formed during themanufacture of Portland cement during the cement kiln stage. As usedherein, “cement clinker” or “Portland cement clinker” refers tonon-hydraulic, non-cementiceous unground Portland cement clinkerparticles. As used herein, “cement clinker” or “Portland cement clinker”does not include conventional cement that is ground up to promote itsreactivity with water to form set cement.

Embodiments of the disclosure include Portland cement clinker LCMs thatinclude Portland cement clinker to mitigate or prevent lost circulationin a well, and thus minimize or prevent fluid loss in, for example,vugular formations. The Portland cement clinker may include clinker ofASTM International Type I cement clinker, ASTM International Type Vcement clinker, API Class A, and API Class G cement clinker. In someembodiments, the cement clinker LCM may also include cement, such as APIClass G cement. In some embodiments, the cement clinker compositionincludes a carrier fluid, such as xanthan gum. In other embodiments, thecarrier fluid may be diutan gum or welan gum. Advantageously, thedifferent particle sizes of the clinker used in the cement clinker LCMcompositions can pack together to form tightly packed plugs ofrelatively low permeability. Moreover, even partial setting of theclinker or cement used in the cement clinker composition can decreasethe permeability of the formed plugs and further improve the mitigationor prevention of loss of wellbore fluids in lost circulation zones.Furthermore, additional advantage includes the provisions for the use ofone or more selected sizes of the clinker to the exclusion of othersizes as LCM materials in wellbore fluids such as aqueous or non-aqueousdrilling fluids or cement slurries.

Embodiments of the disclosure include a cement clinker LCM compositionhaving the cement clinker, the cement, the aqueous carrier fluid, and aninorganic consolidation agent. The inorganic consolidation activator maybe a silicate salt such as sodium silicate. In some embodiments, theinorganic consolidation activator may include, by way of example,calcium aluminate, calcium chloride, sodium aluminate, and potassiumsilicate. In some embodiments, the LCM composition may includecombinations of inorganic consolidation activators, such as sodiumaluminate and potassium silicate. The LCM composition may include theinorganic consolidation activator in an amount in the range of about 1.0w/w % to about 3.0 w/w % by weight of the solids.

Embodiments of the disclosure also include a cement clinker LCMcomposition having the cement clinker and a crosslinked aqueous fluid asthe carrier fluid. In some embodiments, the cross linked fluid is apolyuronide such as an alginate or a pectinate. In such embodiments, thecrosslinking fluid is crosslinked by calcium ions leached or releasedfrom the clinker when mixed with the polyuronide. In some embodiments,the crosslinked fluid is apple pectin, citrus pectin, or sodiumalginate. In some embodiments, the crosslinked fluid is a biopolymercrosslinked with divinyl sulfone (DVS). The biopolymer may includexanthan gum, hydroxyethyl cellulose, diutan gum welan gum, and guar gum,or combinations thereof. For example, in some embodiments thecrosslinking fluid may be a combination of xanthan gum and guar. In someembodiments, the LCM composition includes a weight ratio of biopolymerto DVS in the range of about 1:1 to 1:0.5. In some embodiments, the LCMcomposition having a biopolymer aqueous crosslinking fluid containingDVS may include a base such as sodium hydroxide (NaOH) in an amountsufficient to adjust the pH of the aqueous composition to about 8.5 orgreater, and the aqueous composition may be heated to at least 150° F.until the viscosity begins to increase prior to the addition of clinker.Advantageously, the crosslinked fluids are suitable for effectivelysuspending relatively larger clinker particles (e.g., greater than 1 cm)having a low surface and that are significantly heavier than thecrosslinked fluids. For example, such LCM compositions having acrosslinked fluid may be used with cement clinker having relativelylarger particles, such as clinker with particles having diameter greaterthan 1 cm, greater than 2 cm, greater than 3 cm, or a combinationthereof.

Embodiments of the disclosure further include a cement clinker LCMcomposition having the cement clinker, an aqueous carrier fluid, andpolymer fibers or particulate glass having an aspect ratio greater orless than 1. A particle is said to an “aspect ratio greater or less than1” if the dimensions of the particle in one direction (for example,length) are different than those from another direction (for example,width or radius). The polymer fibers may include polypropylene fibers orpolyacrylonitrile fibers. In some embodiments, LCM composition mayinclude polymer fibers in an amount in the range of 0.25 w/w % to about1.0 w/w %. In some embodiments, the polymer fibers have a length in therange of about 1 mm to about 6 mm. In such embodiments, the LCMcomposition may include particulate glass with an aspect ratio. In someembodiments, the particulate glass may include glass fibers. The lengthof glass fibers may be in the range of about 1 mm to about 6 mm.Alternatively, in some embodiments the glass fibers may be a milled typewith a wider distribution of lengths. The glass fibers may be AlkaliResistant type, or E-glass type in chemical composition. In someembodiments, the particulate glass is of a flake type with varying areasand thickness. The amount of particulate glass used may be in an amountin the range of about 0.25 w/w % to about 2.0 w/w % of the totalcomposition.

The cement clinker LCMs described herein may be mixed with a fluid (forexample, water) and introduced into a lost circulation zone in a well.In some embodiments, after introduction of cement clinker LCM into alost circulation zone, the cement clinker LCM may be maintained incontact with the lost circulation zone for a time period such that theLCM forms plugs in the fractures, gaps, vugs, and other spaces in thelost circulation zone. In some embodiments, the time period may be about24 hours to about 72 hours. In some embodiments, the size (for example,diameter) of the cement clinker particles used in a cement clinker LCMmay be selected based on the type of formation having the lostcirculation zone. For example, cement clinker that includes particleshaving diameters of 3 centimeters (cm) or greater may be selected forlost circulation zones having relatively large fractures and vugs orsmall caverns. Alternatively, sized clinker particles with well-defineddiameters can be employed either by themselves or in combination withother sized clinker particles. For example, clinker particles thatpassed through a US #8 mesh but were retained by #16 mesh can be used bythemselves or in combination with another similarly produced sizedclinker using different combination of sieves. Such sized clinkerparticles can be added to a wellbore treatment fluid such as awater-based or non-aqueous drilling fluid or a cement slurry to stopcirculation losses.

Example Portland Cement Clinker LCM Compositions Using a Carrier Fluidand an Inorganic Consolidation Activator

The following examples are included to demonstrate embodiments of thedisclosure. It should be appreciated by those of skill in the art thatthe techniques and compositions disclosed in the example which followsrepresents techniques and compositions discovered to function well inthe practice of the disclosure, and thus can be considered to constitutemodes for its practice. However, those of skill in the art should, inlight of the present disclosure, appreciate that many changes can bemade in the specific embodiments which are disclosed and still obtain alike or a similar result without departing from the spirit and scope ofthe disclosure.

Example LCM compositions were prepared using different Portland cementclinkers and inorganic consolidation activators. As will be appreciated,the Portland cement clinkers were identified by the cement typesdesignated using ASTM C150/C150M-12, Standard Specification for PortlandCement, ASTM International, West Conshohocken, Pa., 2012, and API Spec.10A, Specification for Cements and Materials for Well Cementing, 23rdedition. 2002. Washington, D.C.: API. Five Portland cement clinkers wereobtained from the following cement types: ASTM International Type Iobtained from Texas Lehigh Cement Company, LP, of Buda, Tex. USA, ASTMInternational Type I from a cement factory, API Class A obtained fromLaFarge Corporation of Chicago, Ill., USA, and ASTM International Type Vand API Class G obtained from a cement factory. The Portland cementclinkers were subjected to sieve separation, and the samples passingthrough a No. 4 mesh sieve were collected for additional testing. Thesieve analysis of the four Portland cement clinkers is shown in Table 1:

TABLE 1 SIEVE ANALYSIS OF PORTLAND CEMENT CLINKERS Wt % in the totalmass Mesh # ASTM ASTM API (Particles Type I Type I ASTM Class Retainedby) (Source 1) (Source 2) Type V G #8 mesh 22 27 23 18 #16 mesh 21 25 1516 Final sample 57 48 62 66

The material that passed through the #4 mesh sieve for each clinker wasused in further testing. The sieve analysis of mixtures of clinkermaterial and ground API Class G cement in a weight ratio of 70:30typically used in well cementing is shown in Table 2:

TABLE 2 SIEVE ANALYSIS OF PORTLAND CEMENT CLINKERS AND CLASS G CEMENTMIXTURES IN 7:3 WEIGHT RATIOS Wt % in the total mass (Clinker Passingthrough #4 mesh : API Class G ground cement = 70:30) Screen # ASTM ASTMAPI (Particles Type I Type I ASTM Class Retained by) (Vendor 1) (Vendor2) Type V G #8 mesh 15 27 17 13 #16 mesh 15 18 11 12 Final sample 70 5572 75

Three different polymers were evaluated for their ability to actsuspending aids (also referred to as “suspending agents”) in water toform the carrier fluid and suspend clinker particles at roomtemperature: diutan gum, xanthan gum, and welan gum. In a typicalprocedure, the polymer is slowly tapped into stirred water. Theagitation rate was kept low (less than 500 revolutions per minute)during a dissolution period of about 30 to about 45 minutes. The weightratio of the carrier fluid to cement solids was maintained at 1:1. Thediutan gum, xanthan gum, and welan gum were each tested atconcentrations of about 0.5 wt % to about 0.8 wt %. Xanthan gum wasfound to be most suitable of the three polymers for providing theparticle suspension at room temperature. Accordingly, subsequentexperiments were conducted using various aqueous xanthan solutions: a0.3 wt % xanthan gum solution, a 0.6 wt % xanthan gum solution, and a0.8 wt % xanthan gum solutions to form the carrier fluid for suspendingclinker particles of different sizes. As described below, varioushydration measurements were conducted. The cement hydration measurementson sieved clinker materials were performed using differential scanningcalorimetry (DSC).

Different inorganic compounds were tested for their ability toconsolidate the clinker slurry. The tested compounds include thefollowing inorganic solids salts and solutions: sodium carbonate,potassium silicate solid, sodium silicate solutions and solids withdifferent sodium hydroxide to silica ratios, sodium aluminate, sodiumhexametaphosphate, calcium chloride, sodium chloride, aluminum sulfate,sodium sulfate, and calcium nitrite.

The testing was conducted using blends of sieved Type I Portland cementclinker and cement kiln dust in various weight ratios and in a 0.8%xanthan gum solution as the carrier fluid. The cement kiln dust wasfound to be less effective than Class G cement in providing particleconsolidation upon curing. Silica flour was also found to be lesseffective than cement kiln dust in its consolidation ability.

Example LCM compositions were formed from different weight ratios ofeach type of Portland cement clinker (ASTM International Type I from afirst source, (ASTM International Type I from a second source, ASTMInternational Type V, and API Class G) and API Class G cement in a 0.8%xanthan gum solution as the suspending medium. The free water separatingduring the curing process was determined from the weight of a curedcement plug as compared to the total slurry weight. The difference inweight after curing was used as the free water that separated during thecuring process.

For each example composition, the free water separated during curing wasdetermined and the state of the plug was evaluated. The results from thetesting are shown in Table 3:

TABLE 3 CURING RESULTS FOR PORTLAND CEMENT CLINKER AND API CLASS GCEMENT COMPOSITIONS Clinker:Class Free Clinker G Water Type Weight ratio(%) Plug Evaluation Type I 90:10 10 Not set, too soft (Source 1) Type I80:20 10 Soft (Source 1) Type I 70:30 10 Rubbery soft (Source 1) Type I60:40 7 Firm with some (Source 1) strength Type I 80:20 None Soft(Source 2) Type V 80:20 16 Soft Class G 70:30 0 Soft Class G 60:40 10Firm

Initial testing was performed using combinations of different particlesize cement clinker fractions in 0.3 wt % diutan gum solutions as thecarrier fluid and sodium silicate. The tests indicated that sodiumsilicate by itself or in combination with soluble carbonate saltsprovided for consolidation of cement particles when cured at elevatedtemperatures.

FIG. 1 is a plot 100 of the heat of hydration of cement clinker (thatis, the fraction of the cement clinker that passed through a US #4 meshscreen) and xanthan gum solution compositions with sodium silicate ascompared to a control composition without sodium silicate. As shown inFIG. 1, the y-axis 102 corresponds to the heat flow in joules/gram (J/g)and the x-axis 104 corresponds to the time in hours. The plot 100depicts the heat of hydration for the following compositions: aclinker-water composition (depicted by line 106), a clinker and xanthangum solution (depicted by line 108), a clinker and xanthan gum solutionwith 1.6 w/w % sodium silicate (depicted by line 110), and a clinker andxanthan gum solution with 0.8 w/w % sodium silicate (depicted by line112). FIG. 1 shows the evolution of the heat of hydration over longerperiods of hydration as compared to the control sample without sodiumsilicate.

Various inorganic consolidation activators were tested using thedifferent Portland cement clinkers and API Class G cement compositionsin xanthan gum solutions. The ASTM International Type I (first source),(ASTM International Type I (second source), and ASTM International TypeV Portland cement clinker compositions were prepared using a 0.8%xanthan gum solution, and the API Class G Portland cement clinkercompositions were prepared using a 0.6% xanthan gum solutions. Two ofthe ASTM International Type I Portland cement clinker compositions alsoincluded polypropylene fibers having a length of 3 millimeters (3 mm).

Each example composition was cured for about 3 days at a temperature ofabout 180° F. The free water separated during curing was determined andthe state of the plug was evaluated. The results from the testing areshown in Table 4:

TABLE 4 CURING RESULTS FOR PORTLAND CEMENT CLINKER AND API CLASS GCEMENT COMPOSITIONS USING VARIOUS INORGANIC CONSOLIDATION ACTIVATORSClinker: Class G cement Free Clinker weight Consolidation Water PlugType ratio Agent (% by wt of cement) (%) Evaluation Class G 60:40Calcium aluminate (1%) 0 Soft Class G 60:40 Calcium chloride (1%) 10Firm Class G 60:40 Sodium aluminate (1%) 6 Firm Class G 60:40 Potassiumsilicate (1%) 6 Firm Class G 60:40 Sodium aluminate (1%) + 0 FirmPotassium silicate (1%) Class G 60:40 Sodium aluminate (0.5%) + 4 FirmPotassium silicate (0.5%) Class G 60:40 Sodium aluminate (0.75%) + 5Firm Potassium silicate (0.25%) Class G 60:40 Sodium aluminate (0.25%) +0 Firm Potassium silicate (0.75%) Type I 60:40 None 9 Intact, not firmType I 60:40 Sodium aluminate (1.2%) 5 Firm Type I 60:40 Potassiumsilicate (1.2%) 2 Firm Type I 60:40 Sodium aluminate (1.2%) + 1 Firm,poor Potassium silicate (1.2%) integrity Type I 60:40 PolypropyleneFiber-3 mm- 14 Intact, Firm (0.5%) (added to mix water) Type I 60:40Sodium aluminate (1.2%) + 1 Intact, Firm Potassium silicate (1.2%) +cylinder Polypropylene Fiber-3 mm- (0.5%) (added to mix water) Type V70:30 None 12 Not set, crumbly Type V 70:30 Sodium aluminate (1.3%) + 3Firm plug Potassium silicate (1.2%) Type V 60:40 None 13 Not set,crumbly Type V 60:40 Sodium aluminate (1.3%) + 3 Very firm, Potassiumsilicate (1.2%) some strength Class G 70:30 Sodium aluminate (1.0%) + 0Not set, Potassium silicate (1.0%) fell apart Class G 60:40 Sodiumaluminate (1.0%) + 3 Not set, Potassium silicate (1.0%) fell apart

As shown in Table 4, various inorganic consolidation activators, whenused with suitable Portland cement clinker and Portland cementcompositions, may enable the formation of settable fluid flow-blockingplugs that may be used to mitigate or prevent lost circulation in a lostcirculation zone.

Example Portland Cement Clinker Compositions Using CrosslinkedPolysaccharides

Example LCM compositions were prepared using API Class A Portland cementclinkers and crosslinked polysaccharides. The API Class A Portlandcement clinker was subjected to sieve separation. The sieve analysis isshown in Table 5:

TABLE 5 SIEVE ANALYSIS OF PORTLAND CEMENT CLINKER Screen # Screen #(Particles (Particles % Particles in Passed Through) Retained by) thetotal mass — 7/16″ 16 7/16″ #4 mesh 19 #4 mesh #8 mesh 19 #8 mesh #16mesh 16 #16 mesh Final sample 30

The bulk of the API Class A Portland cement clinker was sieved using a#4 mesh screen, and the clinker material that passed through the screenwas collected and used for the testing described in this section.Additional Portland cement clinker types were also sieved using a #4mesh screen, collected and used, for the testing described in thissection. The additional Portland cement clinkers were obtained from thefollowing cement types: ASTM International Type I, ASTM InternationalType V, and API Class G.

As discussed above, three different polymers were evaluated for theirability to act suspending aids when dissolved in water to form a carrierfluid and suspend clinker particles at room temperature: diutan gum,xanthan gum, and welan gum. The weight ratio of the carrier fluid tocement solids was maintained at 1:1. The diutan gum, xanthan gum, andwelan gum were each tested at concentrations of about 0.5% to about0.8%. Xanthan gum was found to be the most suitable of the threepolymers for providing the particle suspension at room temperature.Accordingly, subsequent experiments were conducted using a 0.3% xanthangum solution, a 0.6% xanthan gum solution, and a 0.8% xanthan gumsolution as the carrier fluid for suspending clinker particles ofdifferent sizes.

Example Portland cement clinker compositions were prepared using twodifferent types of crosslinking fluids. Biopolymers, such as xanthangum, hydroxyethyl cellulose, diutan gum, welan gum, and guar solutionswere crosslinkined using divinyl sulfone (DVS). The solutions werecrosslinked by heating alkaline solutions of the polymers at about 180°F. and monitoring the viscosities using Brookfield viscometers. The pHof each solution was adjusted to at least 8.5 using a 2% NaOH solution.A 0.8% xanthan gum solution was used and the weight ratio of xanthan gumto DVS was varied from 1:1 to 0.5. A 0.5% diutan gum solution was used,and the weight ratio of diutan to DVS was varied from 1:1 to 1:0.5. Theremaining gum concentrations and DVS ratios were similar to the diutangum solution and ratios. After testing, the xanthan gum, welan gum, anddiutan gum solutions were found to be less susceptible to crosslinkingwith DVS than the random coiled and non-helical polymers such as guarand hydroxyethyl cellulose.

Testing was conducted using clinker particles of relatively largersizes. However, when larger clinker particles—clinker particles thatpassed the 7/16 inch screen but were retained on the No. 4 meshscreen—were added to the xanthan gum solutions, they settled to thebottom. These particles had diameters in the range of about 0.25 inches(0.6 cm) to about 0.58 inches (1.45 cm). The example Portland cementclinkers also had particles larger than this range retained on the 7/16inch screen. An example Portland cement clinker composition was preparedusing a mixture of helical and random coil polysaccharide polymerscrosslinking with DVS, such that one polymer is crosslinked and theother polymer retains its mobility while moving within the crosslinkednetwork. Such compositions provide the flexibility of crosslinked fluidsviscous enough to suspend large clinker particles (for example,particles that passed through the 7/16 inch screen but were retained bythe No. 4 mesh sieve) and form a flowable gel. The particles remainsuspended in the composition without settling in the guar/xanthanmixture under static conditions for more than a month.

FIG. 2 is a plot 200 of the viscosity measurements of varioushydroxyethyl cellulose compositions illustrating the use of DVS as acrosslinking fluid. As shown in FIG. 2, the y-axis 202 corresponds tothe viscosity in centipoise (cP) and the x-axis 204 corresponds to thetime in seconds (sec). The plot 200 in FIG. 2 illustrates the viscosityvs. time for the following compositions heated to about 180° F.: ahydroxyethyl cellulose control composition formed from a 0.5%hydroxyethyl cellulose solution and NaOH (depicted by line 206), ahydroxyethyl cellulose composition formed from a 0.5% hydroxyethylcellulose solution and DVS in a 1:0.5 weight ratio ((depicted by line306), and a hydroxyethyl cellulose composition formed from a 0.5%hydroxyethyl cellulose solution and DVS in a 1:1 weight ratio (depictedby line 308). FIG. 2 depicts the increased viscosity resulting from thecrosslinking of hydroxyethyl cellulose facilitated by the DVS, showingthe suitability as a carrier fluid for the clinker for use as an LCM.

FIG. 3 is a plot 300 of viscosity measurements of various guar gum andxanthan gum compositions illustrating the use of DVS as a crosslinker toform the carrier fluid. As shown in FIG. 3, the y-axis 302 correspondsto the viscosity in centipoise (cP) and the x-axis 304 corresponds tothe time in seconds (sec). The plot 300 in FIG. 3 illustrates theviscosity vs. time for a guar gum and xanthan gum composition formedfrom a 0.5% guar gum solution, xanthan gum, and DVS and having a weightratio of guar gum to DVS of 1:0.5 (depicted by line 306). The plot 300in FIG. 3 also depicts a guar gum and xanthan gum composition formedfrom a 0.5% guar solution and DVS and having a weight ratio of guar toDVS of 1:0.5 (depicted by line 308). FIG. 3 depicts the differentviscosity characteristics resulting from a mixture of helical and randomcoil polysaccharides with the DVS crosslinker as compared to acomposition only having a random non-helical polysaccharide, thusshowing the suitability as a carrier fluid for the clinker having largerclinker particles.

Additionally, example Portland cement clinker compositions were preparedusing a polyuronide carrier fluid. Example Portland cement clinkercompositions were formed using apple pectin at a concentration of 1.5%and citrus pectin at a concentration of 1.5%. A third example Portlandcement clinker composition was formed using commercially availablesodium alginate. The compositions formed highly thixotropic,non-settling slurries at room temperature. The compositions were storedat about 180° F., causing syneresis of the fluid with the formation offree water. Both the example alginate and the pectins formed gels in thepresence of calcium ions present upon dissolution of a small amount ofclinker. The calcium ions dissolved from the clinker enable theformation of “egg-crate” calcium complexes with the example alginate orpectins, showing the suitability as a carrier fluid for the clinker foruse as an LCM. Such compositions thus are also suitable of suspension ofclinker for use as an LCM, especially as a carrier fluid for clinkerhaving larger clinker particles.

Example Portland Cement Clinker Compositions Using High Aspect RatioMaterial

Example LCM compositions were prepared using API Class A Portland cementclinkers and high aspect ratio materials. The API Class A Portlandcement clinker was subjected to sieve separation. The sieve analysis isshown in Table 6:

TABLE 6 SIEVE ANALYSIS OF PORTLAND CEMENT CLINKER Screen # Screen #(Particles (Particles % Particles in Passed Through) Retained by) thetotal mass — 7/16″ 16 7/16″ #4 mesh 19 #4 mesh #8 mesh 19 #8 mesh #16mesh 16 #16 mesh Final sample 30

The bulk of the API Class A Portland cement clinker was sieved using a#4 mesh screen, and the clinker material that passed through the screenwas collected and used for the testing described in this section.Additional Portland cement clinker types were also sieved using a #4mesh screen, collected and used, for the testing described in thissection. The additional Portland cement clinkers were obtained from thefollowing cement types: ASTM International Type I, ASTM InternationalType V, and API Class G.

As discussed above, three different polymers were evaluated for theirability to act as suspending aids when dissolved in water to from thecarrier fluid and suspend clinker particles at room temperature: diutangum, xanthan gum, and welan gum. The weight ratio of the carrier fluidto cement solids was maintained at 1:1. The diutan gum, xanthan gum, andwelan gum were each tested at concentrations of about 0.5% to about0.8%. Xanthan gum was found to be the most suitable of the threepolymers for providing the particle suspension at room temperature.Accordingly, subsequent experiments were conducted using a 0.6% xanthangum solution and a 0.8% xanthan gum solution as the carrier fluid forsuspending clinker particles of different sizes.

As described below, various hydration measurements were conducted. Thecement hydration measurements on sieved clinker materials were performedusing differential scanning calorimetry (DSC) at 25° C. and 70° C.

Loss circulation measurements were performed using a kitchen doughextruder having a hand-squeezable piston, such as an extruder used tosqueeze and extrude dough into strands. Discs having different holedimensions and geometries, including circular holes of differentdiameters and slits of different widths, were used to simulate losscirculation geometries. An example cement clinker compositions suspendedin 0.8% xanthan gum solution was prepared by mixing a 1:1 weight ratioof clinker to xanthan gum solution. The paste was transferred to thetesting apparatus with the preassembled lid containing the piston, andthe bottom lid containing the disc with the desired hole dimensions andgeometries was attached. A Teflon tape was used to the cover the threadson the outside of the main cylinder of the testing apparatus to providea leak-proof seal. Pressure was applied by hand-squeezing the pistonuntil the flow of filtrate exiting the testing apparatus stopped. Theweight of the filtrate was measured. The testing apparatus wasdissembled, and the filter cake was removed.

The strength of the filter cake material was measured by packing thecake into a cell of an Ultrasonic Cement Analyzer (UCA) manufactured bythe Chandler Equipment Company of Springdale, Ariz., USA, and thestrength development was monitored at a test temperature. When thestrengths leveled off, the measurement was stopped.

The example cement clinker compositions were also optimized for particlesize distribution for development of structural integrity uponplacement. The structural integrity was determined by curing the cementslurry at 180° F. in the range of about 2 days to about 3 days andvisually inspecting the formed plug. The compositions were optimized byblending cement clinker with a ground oil well cement (API Class Gcement) in different clinker to ground cement ratios. The plugs formedby the example compositions was compared to the plug integrity of theplug formed from a composition of 100% clinker. The comparison wasperformed by determining the ease by which the set plug demolded as anintact cylinder from a 1.5 inch (diameter)×9 inch (length) cylindricalbass mold, and by the plug integrity and the strength to touch of thedemolded plugs. The molds were cured in a water bath at about 180° F.for about 48 hours to about 72 hours.

FIG. 4 is a plot 400 of the heat of hydration of different clinkercompositions having different particle sizes of ASTM Type I cementclinker. As shown in FIG. 4, the y-axis 402 corresponds to the heat flowin milliwatt/gram (mW/g) and the x-axis 404 corresponds to the time inhours. The plot 400 depicts the heat of hydration for the followingcompositions: a clinker composition having No. 4 mesh retained particles(depicted by line 406), a clinker composition having No. 8 mesh retainedparticles (depicted by line 408), a clinker composition having No. 16mesh retained particles (depicted by line 410), and the composite of theclinker particles that passed the No. 16 mesh.

FIG. 5 is a plot 500 of the cumulative heat of hydration of two clinkerparticle sizes of ASTM Type I Cement. As shown in FIG. 5, the y-axis 502corresponds to the cumulative heat of hydration in joules (J) and thex-axis 504 corresponds to the hydration time in hours. The plot 500depicts the heat of hydration for a clinker composition having No. 4mesh retained particles (depicted by line 506) and a clinker compositionhaving No. 16 mesh retained particles (depicted by line 508),

The heat of hydrations shown in FIGS. 4 and 5 are consistent with theexpected relationship between particle sizes, surface areas, andreactivity with water. That is, smaller particles hydrated and generatedmore heat than larger particles. The heat generated due to the hydrationis an indicator of subsequent strength development. The results showthat by controlling the amount of fine cement particle content, thestrength of the cement plug can be controlled.

Various example Portland cement clinker compositions were prepared withand without fibers or flakes using a 0.8% xanthan gum solution. In theexample compositions that included high aspect ratio materials such asdifferent fibers or flake materials, the materials were dry blended intothe cement or pre-dispersed into the mixing fluid. The glass flakes wereof thickness in the range of about 6.5 μm to about 8.5 μm with 80% ormore particles in the range of about 150 μm to about 1700 μm.

The weight of the filter cakes and the weight of the filtrate for eachexample composition were measured. In some embodiments, the compositionswere prepared using RadiLock fibers available from Bossco Industries ofHouston, Tex., USA. Table 7 depicts the results of for each examplePortland cement clinker composition with or without fibers and screentype

TABLE 7 RESULTS OF FILTER CAKE FORMATION FOR EXAMPLE PORTLAND CEMENTCLINKER COMPOSITIONS WITH AND WITHOUT FIBERS Fiber type Fiber Filtercake Filtrate and amount weight weight Screen Clinker Class size (w/w %)(grams) (grams) Regular 100 52 27 Regular 90 10 52 26 Regular 80 20 5814 Regular 70 30 56 25 Wide hole 100 47 30 Wide hole 70 30 55 19 Regular100 Radilock- 0.5% 49 28 1.8 mm Regular 80 20 Radilock- 0.5% 54 24.5 3mm pre- (watery dispersed thin) Regular 70 30 Radilock- 0.5% 53.3 24.8 3mm pre- dispersed Regular 100 Radilock- 0.5% 53 26 (gel) 3 mm Regular100 Radilock- 0.5% 52 27 6 mm Regular 100 Glass-   1% 52 25 3 mm Regular80 20 Glass- 0.5% 53 26 3 mm pre- (watery dispersed thin) Regular 100Glass- 0.5% 3 mm Regular 100 Particulate 0.5% 49 28 glass-large WideSlit 100 46 29 (gel) Wide Slit 90 10 54 23 (gel) Wide Slit 70 30 57 20(watery thin) Narrow 100 51 24 Slit Narrow 90 10 59 19 Slit

FIG. 6 is a plot 600 of the filter cake strength (as indicated by theUCA strength) for various Portland cement clinker compositions havingClass G cement with and without fibers. As shown in FIG. 6, the y-axis602 corresponds to the UCA strength in pounds per square inch (psi) andthe x-axis 604 corresponds to the time in hours. FIG. 6 depicts the UCAstrength for the following example compositions: a Portland cementclinker:cement weight ratio of 7:3 with 0.5 w/w % polypropylene fibers(depicted by line 606); a Portland cement clinker:cement weight ratio of7:3 without fibers (depicted by line 608); a Portland cementclinker:cement weight ratio of 7:3 with 0.25 w/w % polypropylene fibers(depicted by line 610); a Portland cement clinker:cement weight ratio of7:3 with 0.5 w/w % polyacrylonitrile (PAN) fibers (depicted by line612); and a Portland cement clinker:cement weight ratio of 4:1 withoutfibers (depicted by line 614).

As shown in FIG. 6, polypropylene fibers at 0.5 w/w % provided higherstrengths than at a lower concentration of 0.25 w/w %. The filter cakestrength observed for the composition having polyacrylonitrile (PAN)fibers was lower than the filter cake strength observed for thecomposition having polypropylene fiber when used in identical amounts(0.5 w/w %). The polypropylene fibers were coated with a dispersantcoating for efficient dispersion upon addition to water. The separationof fibers into individual filaments was more efficient and complete uponaddition to water than the polyacrylonitrile fibers.

Portland Cement Clinker LCM Compositions and Use

Embodiments include a lost circulation material (LCM) composition formedfrom Portland cement clinker and a carrier fluid (for example, anaqueous carrier fluid). The Portland cement clinker may ASTMInternational Type I cement clinker, ASTM International Type V cementclinker, API Class A, and API Class G cement clinker. In otherembodiments, other cement types that produce suitable cement clinker maybe used. In some embodiments, an LCM composition includes cement. Insome embodiments, the cement used in the LCM composition may be APIClass G cement. In other embodiments, other cement types that providesuitable particle consolidation upon curing of the composition may beused. In some embodiments, the weight ratio of cement clinker to cementin the range of about 60:40 to about 90:10.

In some embodiments, the size (e.g., diameter) of the particles of thecement clinker used in the cement clinker LCM composition may beselected based on a lost circulation zone, such as based on thedimensions of openings in the lost circulation zone. For example, cementclinker that includes particles having diameters of 3 centimeters (cm)or greater may be selected for lost circulation zones having relativelylarge fractures and vugs or small caverns.

In some embodiments, the suspending agent used to form the carrier fluidmay be xanthan gum. For example, in some embodiments, the carrier fluidmay be a 0.3 wt % xanthan gum aqueous solution, a 0.6 wt % xanthan gumaqueous solution, or a 0.8 wt % xanthan gum aqueous solution. In otherembodiments, the carrier fluid may be diutan gum or welan gum.

In some embodiments, the cement clinker LCM composition includes aninorganic consolidation activator, so that the cement clinkercomposition includes Portland cement clinker, cement, a carrier fluid,and the inorganic consolidation activator. In some embodiments, theinorganic consolidation activator may be a silicate salt such as sodiumsilicate. In some embodiments, the inorganic consolidation activator mayinclude the following activators: calcium aluminate, calcium chloride,sodium aluminate, and potassium silicate, and any combination thereof.In some embodiments, the LCM composition may include combinations ofinorganic consolidation activators, such as sodium aluminate andpotassium silicate.

In some embodiments, the LCM composition may include an inorganicconsolidation activator (or combination of inorganic consolidationactivators). Thus, in such embodiments, the LCM composition may includePortland cement clinker, cement, a carrier fluid, and an inorganicconsolidation activator. In some embodiments, LCM composition includesthe inorganic consolidation activator in an amount in the range of about1.0 w/w % to about 3.0 w/w %. For example, in some embodiments havingtwo inorganic consolidation activators, the LCM composition may includea first inorganic consolidation activator in the range of 0.25 w/w % toabout 1.5 w/w % and a second organic consolidation activator in acorresponding amount in the range of about 0.25 w/w % to about 1.5 w/w%.

In some embodiments, the cement clinker LCM composition includes acrosslinked fluid as the carrier fluid. In some embodiments, thecrosslinking fluid is a polyuronide. In such embodiments, the cementclinker LCM composition includes Portland cement clinker, a carrierfluid, and the crosslinking fluid. The polyuronide may include, forexample, alginates and pectinates. In some embodiments, the polyuronidemay be apple pectin, citrus pectin, or sodium alginate. In someembodiments, the LCM composition may include the polyuronidecrosslinking fluid in an amount of 0.5 w/w % by weight of water to about3 w/w % by weight of water. In such embodiments, the crosslinking fluidis crosslinked by calcium ions leached or released from the clinker whenmixed with the polyuronide.

In other embodiments, the crosslinking fluid is a biopolymer crosslinkedusing divinyl sulfone (DVS). In such embodiments, the cement clinker LCMcomposition includes Portland cement clinker, a carrier fluid, thebiopolymer crosslinking fluid, and DVS. In such embodiments, thecrosslinking fluid may include xanthan gum, hydroxyethyl cellulose,diutan gum welan gum, and guar gum, or combinations thereof. Forexample, in some embodiments the crosslinking fluid may be a combinationof xanthan gum and guar. In some embodiments, LCM composition mayinclude a biopolymer crosslinking agent in an amount of about 0.5 w/w %to about 0.8 w/w %. In some embodiments, the LCM composition includes aweight ratio of biopolymer to DVS in the range of about 1:1 to 1:0.5. Insome embodiments, the LCM composition having a biopolymer crosslinkingfluid may include a base such as sodium hydroxide (NaOH) in an amountsufficient to adjust the pH of the LCM composition to about 8.5 or, insome embodiments, greater than 8.5. In such embodiments, prior toaddition of the clinker, the biopolymer aqueous solution may be mixedwith DVS and sufficient sodium hydroxide added to raise the pH to 8.5,following by heating to at least 150° F. until the viscosity begins toincrease. In some embodiments, an LCM composition having a crosslinkedfluid as the carrier fluid may include cement clinker having particleswith a diameter greater than 1 cm, greater than 2 cm, greater than 3 cm,or a combination thereof. In some embodiments, the cement clinker mayinclude particles defined by one or more mesh sizes, such that thecement clinker excludes particles outside of those defined by the one ormore mesh sizes. For example, the cement clinker particles may onlyinclude particles passed by a first mesh size but retained on a secondmesh size. In some embodiments, the cement clinker particles may besized based on the sizes of fractures in a lost circulation zone. Forexample, in such embodiments, the D50 particle size distribution of thecement clinker particles may be ⅓ of the width of fractures in the lostcirculation zone (e.g., ⅓ the width of the average fracture size in thelost circulation zone).

In some embodiments, the cement clinker LCM composition includes polymerfibers. In such embodiments, the cement clinker LCM composition includesPortland cement clinker, cement, a carrier fluid, and polymer fibers. Insome embodiments, the polymer fibers are polypropylene fibers. In someembodiments, the polypropylene fibers may be coated with a dispersant toimprove the dispersion in water. In some embodiments, the polymer fibersare polyacrylonitrile fibers. In other embodiments, other suitablepolymer fibers may be used. In some embodiments, LCM composition mayinclude polymer fibers in an amount in the range of 0.25 w/w % to about1.0 w/w %. In some embodiments, the polymer fibers have a length in therange of about 1 mm to about 6 mm.

In some embodiments, the cement clinker LCM composition includesparticulate glass with an aspect ratio greater or less than 1. In suchembodiments, the cement clinker LCM composition includes Portland cementclinker, cement, a carrier fluid, and particulate glass. In suchembodiments, the LCM composition may include particulate glass in anamount in the range of about 0.25 w/w % to about 2.0 w/w %. In someembodiments, the particulate glass may be glass fibers having a lengthin the range of about 1 mm to about 6 mm.

The cement clinker LCM compositions described herein may be used in avariety of manners to mitigate or prevent lost circulation in a lostcirculation zone. The cement clinker LCM compositions may be mixed witha fluid, such as water or a drilling fluid, and introduced (e.g.,pumped) downhole at parameters (pump rate, pressure, etc.) sufficient toposition the cement clinker LCM composition into contact with a lostcirculation zone, such that the cement clinker LCM alters the lostcirculation zone. In some embodiments, the cement clinker LCMcompositions may be formed as a fluid pill and introduced (e.g., pumped)downhole to contact a lost circulation zone. The cement clinker LCMcompositions described herein may be used, for example, during drillingoperations, cementing operations, or other operations for which reducingor prevent loss of fluid is desirable.

In some embodiments, the cement clinker LCM compositions may be allowedto interact with the lost circulation zone for a period to enable thein-situ formation of solids as a result of the interaction between thecomponents of the cement clinker LCM composition. The formed solids mayalter the lost circulation zone (for example, by entering and blockingporous and permeable paths, cracks, and fractures in a formation in thelost circulation zone, such as forming a structure in a mouth or withina fracture). In some embodiments, the interaction period may be in therange of about 24 hours to about 72 hours.

The cement clinker LCM compositions may provide for easier pumping ofthe LCM due to the suspension of the clinker particles. Moreover, theenvironmentally friendly properties of the cement clinker LCMcompositions may minimize or prevent any environmental impact and effecton ecosystems, habitats, population, crops, and plants at or surroundingthe drilling site where the cement clinker LCM compositions are used.

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Elements and materials may be substituted for those illustrated anddescribed in the disclosure, parts and processes may be reversed oromitted, and certain features may be utilized independently, all aswould be apparent to one skilled in the art after having the benefit ofthis description. Changes may be made in the elements described in thedisclosure without departing from the spirit and scope of the disclosureas described in the following claims. Headings used described in thedisclosure are for organizational purposes only and are not meant to beused to limit the scope of the description.

What is claimed is:
 1. A method to control lost circulation in a lostcirculation zone in a wellbore, comprising: introducing a lostcirculation material (LCM) into the wellbore such that the LCM contactsthe lost circulation zone and reduces a rate of lost circulation intothe lost circulation zone as compared to a period before introducing theLCM, wherein the LCM comprises: Portland cement clinker, wherein thePortland cement clinker consists of non-hydraulic, non-cementiceousunground Portland cement clinker particles; cement; a carrier fluid; andan inorganic consolidation activator selected to consolidate the clinkerin the LCM to form a plug when introduced into a lost circulation zone.2. The method of claim 1, wherein the carrier fluid comprises an aqueouscarrier fluid that includes at least one of diutan gum, xanthan gum, andwelan gum.
 3. The method of claim 1, wherein the Portland cement clinkercomprises ASTM International Type I cement clinker, ASTM InternationalType V cement clinker, API Class A cement clinker, or API Class G cementclinker.
 4. The method of claim 1, wherein the cement comprises APIClass G cement.
 5. The method of claim 1, wherein the inorganicconsolidation activator comprises a silicate salt.
 6. The method ofclaim 1, wherein the inorganic consolidation activator comprises atleast one of sodium silicate, calcium aluminate, calcium chloride,sodium aluminate, and potassium silicate.
 7. The method of claim 1,wherein the inorganic consolidation activator comprises an amount in therange of about 1.0 weight of the total weight (w/w %) to about 3.0 w/w%).
 8. The method of claim 1, wherein the weight ratio of carrier fluidto clinker is 1:1.
 9. The method of claim 1, wherein the weight ratio ofcement clinker to cement is in the range of 60:40 to 90:10.
 10. Themethod of claim 1, comprising maintaining the LCM in contact with thelost circulation zone for a time period, such that the LCM forms atleast one plug.
 11. The method of claim 10, wherein the time period isin the range of 24 hours to 76 hours.
 12. The method of claim 1, whereinthe lost circulation zone is located in a karst formation.
 13. Themethod of claim 1, wherein introducing the lost circulation material(LCM) into the wellbore comprises: mixing the LCM with water to form amixture; and pumping the mixture into the lost circulation zone.